Frame Identity

[Tahitian_Red]

I'm trying to identify this frame.  The frame number is 7-21058356









Thanks for any help!

The Factory Novice

[Rocket]

The frame was built in October 1972 for a 175 Jackpiner, probably considered a 1973 model.
Rocket

[Paul Danik]

T-R,

   Most likely the information that Rocket supplied you is all that you needed, but those frames are pretty interesting, at least to me.

   When the KTM Jackpiner engine was first put into production, KTM took the same frame that they were putting the Sachs 100 and 125cc engines into and changed the motor mounts to hold the Jackpiner engine. The 7 prefix in your serial number indicates that the bike is a Jackpiner, not a Sachs powered Six-Day or Berkshire. If you decide to build a bike around that frame, MOST everything that you need is the same as the Sachs powered machines.

   Here is a link to a picture of a Jackpiner in a frame such as yours.  http://gallery.pentonusa.org/gallery/album06/DSC09464

Hope this helps.
Paul

[Tahitian_Red]

So, the Jackpiner frame uses the short style seat?  Does it also have a different tank since the frame backbone is narrow?  I thought I might use this frame to put together a lightweight (lighter weight?) 250 MX Vintage bike.  Will the 74-75 swingarms work on this frame?  

Thanks again for the help!

The Factory Novice

[brian kirby]

Jay,

The first Jackpiner came out on '72 so it had the short seat, "toaster" tank and alloy fenders. If you look at the bike in the link Paul put up, that is exactly what this bike you have looked like. I dont know about the later swing arm, but someone here will know.

Brian

'73 Berkshire

[Tahitian_Red]

I guess that the 73 Jackpiner is the frame to have then?  

I weighed a 74 frame against the Jackpiner frame, on a not so accurate bathroom scale and got about a 5 lbs difference.  I would imagine with the swingarms installed the difference would 6-7 lbs total.  Does that sound about right?

The Factory Novice

[gooddirt]

First what do you want to build?  Race- Show or Trail- The 72-73  Jackpiner geometry is just about spot on if not the same as the 125 Six day frame.  You can also put any KTM motor in this frame; 32mm or 35mm forks of your liking. You can use any seat combo short -short /short- tall/ long- tall and any early CMF gas tank.  Put a 250 or 400 KTM motor in it and 35mm forks and you will have a monster[:0]. (got decals)  Good luck.  LG

[brian kirby]

Jay, if you are not going to build a show bike this is what I would do.

Like LG said above, I would find a 250 (or 400) engine, 35mm forks and build a killer Sportsman 250. The early frame has better geometry than the later frame and is also lighter. The 74.5 frame and swing arm both have a lot of excess weight related to the "laydown" shock mounting that is dead weight if you are using the upright Vintage shock position. The early swing arm that came with that bike is just as good for Vintage as the later multi position swing arm, but is much lighter.

That combination would be better than ANY other bike in sportsman 250 and would eat Elsinores for lunch because it would actually turn.

Brian

'73 Berkshire

[Dennis Jones]

+ 1 on what the other guys said. This frame makes a great vintage racer. My vintage CC racer is based on one. With a 175 motor in it, it is a very competitve 0-200 sportman class bike. I've rode mine to an AHRMA class championship and I'm an average at best rider.

Something not mentioned that I think is important is the brake pedal and linkage. On this frame the pedal starts under the peg, goes under the frame, and down the left side of the swingarm ala the 125 and 100 bikes. Nothing ever wears out on this setup. On the 74 and up frames the pedal starts over the peg and goes straight down the right side to the brake arm. While one would think this is simpler and better, EVERYTHING wears out on it. The frame to pedal pivot, the brake arm to pedal pivot, and worst of all the rear backing plates are almost always worn. The design just pulls sideways on everything.

HAPPY NEW YEAR - GO PENTON

Dennis Jones

[Tahitian_Red]

Thanks for the info guys!

LG,

I will be ordering the decals as soon as I get back from Tahoe.  Happy New Year to all!!!


The Factory Novice